1. Field of the Invention
Embodiments of the invention generally relate to tools having a seal assembly for sealing an annulus between a tubular seat in the wellbore and the outside of the tool disposed in the tubular seat.
2. Description of the Related Art
Surface-controlled, subsurface safety valves (SCSSVs) and plugs are commonly used to shut-in oil and/or gas wells. The SCSSV or plug fits into tubing in a hydrocarbon producing well and operates to block upward flow of formation fluid through the tubing. The tubing may include a landing nipple designed to receive the SCSSV or plug therein such that the SCSSV or plug may be installed and retrieved by wireline. During conventional methods for run-in of the SCSSV or plug to the landing nipple, a tool used to lock the SCSSV or plug in place within the nipple also temporarily holds the SCSSV or plug open until the SCSSV or plug is locked in place.
Most SCSSVs are “normally closed” valves, Le., the valves utilize a flapper type closure mechanism biased to a closed position. During normal production, application of hydraulic fluid pressure transmitted to an actuator of the SCSSV maintains the SCSSV in an open position. A control line that resides within the annulus between production tubing and a well casing may supply the hydraulic pressure to a port in the nipple that permits fluid communication with the actuator of the SCSSV. In many commercially available SCSSVs, the actuator used to overcome the bias to the closed position is a hydraulic actuator that may include a rod piston or concentric annular piston. During well production, the flapper is maintained in the open position by a flow tube acted on by the piston to selectively open the flapper member in the SCSSV. Any loss of hydraulic pressure in the control line causes the piston and actuated flow tube to retract, which causes the SCSSV to return to the normally closed position. Thus, the SCSSV provides a shutoff of production flow once the hydraulic pressure in the control line is released.
The landing nipple within the tubing may become damaged by operations that occur through the nipple prior to setting the SCSSV or plug in the landing nipple. For example, operations such as snubbing and tool running using coiled tubing and slick line can form gouges, grooves, and/or ridges along the inside surface of the nipple as the operations pass through the nipple. Further, any debris on the inside surface of the nipple or any out of roundness of the nipple may prevent proper sealing of the SCSSV or plug within the nipple. Failure of the SCSSV or plug to seal in the nipple due to surface irregularities in the inner diameter of the nipple can prevent proper operation of the actuator to open the SCSSV and can prevent the SCSSV or plug from completely shutting-in the well when the SCSSV or plug is closed since fluid can pass through the annular area between the SCSSV or plug and the nipple due to the irregularities. Operating the well without a safety valve or with a safety valve or plug that does not function properly presents a significant danger. Thus, the current solution to conserve the safety in wells having damaged nipples includes an expensive and time consuming work over to replace the damaged nipples.
Therefore, a need exists for improved apparatus and methods for disposing a plug or SCSSV within tubing regardless of whether the tubing has a damaged or irregular inside surface.